Facebook has been a hive of activity this week. The social network’s Messages app has been updated and now looks more like an email inbox, iOS users have been treated to a completely re-written Facebook app, and the FTC has green-lighted the pre-IPO acquisition of popular photo app Instagram.

The FTC cleared the $1 billion purchase saying that the popular photo upload service has no revenues and as such, the merger would not create a monopoly. “We are pleased that the Federal Trade Commission has cleared the transaction after its careful and thorough review,” Facebook said.

Meanwhile, the changes made to Messages are in line with the company’s plans to make it a fully-fledged email client, and brought a host of under the hood improvements. The refreshed interface uses a new two-pane layout with all messages on the left, and the content of each one on the right pane.

Facebook also released a completely re-written app for iPhone and iPad users yesterday, moving away from HTML5 and returning to Objective-C, which should respond to commands twice as fast. “The three things we really focused on were opening the application, scrolling through the news feed and tapping into and viewing a photo. So we made all those things twice as fast,” Mick Johnson, a product manager at Facebook said.

If all that wasn’t enough, Peter Thiel of PayPal fame and one of Facebook’s earliest backers with a 10% stake in the company, dumped 80% of his shares once the lock-up ended. The move raised $395.8 million but led many to question why he sold his shares so quickly, adding to the already precarious stock price since its IPO.

Nevertheless, shares in Facebook rose slightly by 1.5% to $19.44 during trading on the Nasdaq stock market yesterday, down 49% from $38 apiece when the company first traded on May 17.